Interesting thoughts. Thanks for mentioning them.

I remember now my father (GM engineer, mostly safety related projects, in the 60's & 70's) telling me to use recirculate when I bought a new car with fancy air conditioning (to impress girls, I suppose).
He was funny- Why do we need A/C when the windows open? At home- Same thing for A/C & the furnace stayed at 60 because "we each have sweaters". Why get a car radio when we all speak the same language & can converse? Smart man- Wise, too.